This application claims the priority of Japanese Patent Application No.8-317017(317017/1996) filed on Nov. 12, 1996, which is incorporated herein by reference.
Three types of data processing methods have been proposed for inputting, storing and regenerating continual-tone pictures.
(A) Bit map data method which treats the data of object pictures as an assembly of bit map data.
(B) Discrete cosine transformation method (DCT method) which compresses the image data by the discrete cosine transformation.
(C) Function-approximation method which approximates the image data by a special function.
The three prior methods are explained in short.
(A) Bit Map Data Method
The bit map data method is the most popular method of processing continual-tone pictures by dissolving the object pictures into individual pixels, determining the tone-values (degrees of tones) of the individual pixels, memorizing the tone-values of all the pixels as they are without data compression, and regenerating the pictures from the memorized data of tone-values directly. The method stores all the tone-data of all the pixels in memories. The process is so simple that many people adopt the bit map method for treating continual-tone pictures at present.
Nevertheless, this method is annoyed at an enormous amount of data, because the method must memorize the crude tone data of all the pixels. Such a huge amount of data brings about a fatal drawback to the bit map data method. The treatment of the huge data requires a big capacity of memory and a long time for processing.
Besides, the method tries to enlarge, reduce or transform an object picture by enlarging, reducing or transforming the coordinates of all the related pixels directly, since all the tone data are stored as the inherent values of individual pixels. The bit map calculation degrades the quality of the regenerated pictures. The peripheries of individual image components are often blurred. Some people proposed improvements for overcoming the inherent defects of the bit map data method.
1 W. K. Pratt:"Digital Image Processing", Wiley Interscience, New York (1978).
2 (J. A. Parker, R. V. Kenyon and D. E. Troxel:"Comparison of Interpolating Methods for Image Resampling", IEEE Trans. MI, MI-2, 1, pp.31-39 (1983).
3 Kazuo Toraichi, Masaru Kamada, Satomi Ishiuchi, Sai Yang and Ryoichi Mori,"Improvement of Video Hardcopy Image Quality by using Spline Interpolation", Trans. IEICE Jpn (D) vol. J71-D, No.7, pp.1276-1285 (1988).
4 Akira Tanaka, Hideyuki Imai, Masaaki Miyakoshi, Jun Date, "Enlargement of Digital Images by Multiresolution Analysis", Trans. IEICE Jpn (D-II) vol. J79-D-II, No.5, pp819-825 (1996).
1 and 2 suggested improvements of interpolating the bit map data by the sinc function, and outputting the interpolated data. 3 proposed another improvement of interpolating the bit map data by using piecewise polynomials, and outputting the interpolated data. 4 tried to analyse the bit map data by the multiresolution way with a plurality of degrees of resolution and interpolate the bit map data by the analysis, and output the data interpolated by the multiresolution analysis. These trials are capable of enlarging or reducing the pictures, since unknown data are obtained by interpolating according to some rules. These improvements are still annoyed at an enormous amount of the bit map data, since they store the parameters of the object pictures as the bit map data, and they enlarge, reduce or regenerate the pictures from the stored bit map data. Therefore, these proposals cannot give the final solution for the inherent difficulty of the bit map data method.
(B) Discrete Cosine Transformation Method (DCT Method)
The discrete cosine transformation method is effective for such a picture having continually-changing tones but is incompetent for a picture in which the tone changes drastically. The discontinuity of the tone gives the DCT method the block distortion or the edge degeneration. The incompetence for the quick-changing tone induces a fatal drawback of degrading the quality of the picture in the case of the picture including various types of images. Another weak point is the degeneration accompanying the enlargement of the object picture. The enlargement, the reduction or the transformation degrades the quality of the picture. Someone proposed improvements of the DCT method for suppressing the degradation of the quality. The trials are still insufficient for overcoming the difficulties.
5 Koichi Fukuda, Hirohiko Minakuchi, Akira Kawakami,"Encoding Method of Static Pictures by applying the AR assumption on the DCT of edge-blocks", Trans. IEICE Jpn (D-II) J76-D-II, 4 pp827-834, (1993).
6 Eiji Shinbori and Mikio Takagi,"High quality enlargement of pictures by applying the Gerchberg-Papoulis' repetition method on the DCT", Trans. IEICE Jpn (D-II) J76-D-II, No.9, pp.1932-1940 (1993).
5 proposed an improvement of the DCT method for suppressing the degeneration of quality of edge portions by the AR assumption. 5 however, is incompetent for the enlargement, the reduction or the transformation. 6 suggested a method for solving the problem of the degradation of the edge portions in enlargement by the quasi-revival processing. Being annoyed at an enormous amount of data, these improvements are still inoperative for the problems which this invention intends to solve. PA1 (1) automatic compression of data of continually tone-changing pictures, PA1 (2) feasible enlargement, reduction and transformation of continually tone-changing pictures, and PA1 (3) a small number of data for memorizing the object pictures. The abovementioned prior art 1 to 10 cannot satisfy all the three requirements.
(C) Function-Approximation Method
This method tries to approximate the parts of pictures by some functions.
7 Takahiko Horiuchi, Yasuhiro Ohtaki, Kazuo Toraichi, "Multistep deduction of joint points for automatic approximation of multi-fonts", Trans. IEE Jpn(C), vol.113-C, No.12, pp.1136-1143, (1993).
8 Japanese Patent Application No.4-259137(259137/'92).
9 Japanese Patent Application No.4-269646(269646/'92).
10 K. Toraichi, T. Horiuchi, R. E. Kalman, Y. Ohtaki and H. Nagasaki, "Compressing Data volume of Left Ventricular Cineangiograms", IEEE Trans. BME, vol.40, No.6, pp.579-588 (1993).
The three treatises 7 to 9 aim not at continually-changing tone pictures but at binary tone pictures which have only white pixels and black pixels and lack medium-steps of tone. These methods deduce outlines of black parts and process the outlines. Therefore, these methods are fully incompetent for continually-changing tone pictures, e.g., photographs, in which peripheral lines cannot be clearly defined. The binary tone methods are incapable of treating continually-changing tone pictures.
10 it suggested a way of processing medical-purposed continually-changing tone pictures by approximating all the horizontal lines of pixels from the left to the right by special functions, i.e., the raster order. We assume that the picture has I pixels in the x-direction and has J pixels in the y-direction. The x-direction is defined from the left to the right in the horizontal line. The y-direction is defined from the top to the bottom in the vertical line. I and J are big numbers, e.g., 512 to 2048. Since
10 must approximate the whole of the I pixels aligning in a horizontal line having a big variation of tones by a set of special functions without serious discrepancy from the crude tone values of the pixels, the approximation functions must be an assembly of polynomials of high orders. Using high order functions so as to approximate plenty of tone values of all the pixels aligning in horizontal lines, 10 will suffer from a great many parameters which define the high order approximation functions. An excess number of parameters prohibits 10 from compressing the data for storing in memories. The number of parameters is one drawback. There is still a more serious difficulty in the raster order approximation method 10. It is the y-direction discontinuity of the approximation functions. The raster order scanning approximation method respects the continuity in the x-direction but ignores the continuity in the y-direction. Thus severe discontinuity often appears in the y-direction in regeneration of the pictures. The y-direction discontinuity degenerates the quality of regenerated pictures, in particular, in the case of enlargement. The raster scanning approximation method 10 is fully incapable of rotation or anisotropic enlargement of pictures.
The discontinuity in the y-direction and the impossibility of enlargement or transformation are inherent and serious difficulties of the raster order approximation method 10 which scans a picture in the raster order, accumulates the data in the same order and approximates the linearly-aligning data by some functions. Thus the raster order scanning approximation method is still incompetent for the problems this invention attempts to solve. Namely, there is no effective method for processing continually-changing tone pictures yet.
The Problems to be Solved
Objects of this invention are now described in brief;
A purpose of the present invention is to provide an inputting and outputting method and apparatus for continually-changing tone pictures including the steps of reading in optically or making originally continually-changing tone pictures, compressing the image data, storing the compressed data in memories, and regenerating the pictures in an arbitrary scale at an arbitrary position in a short time. Another purpose of the present invention is to provide an inputting and outputting method and apparatus capable of compressing automatically the image data of continually-changing tone pictures. A further purpose is to provide an inputting and outputting method and apparatus capable of enlarging, shrinking or transforming continually-changing tone pictures without degenerating the quality of the pictures. A further purpose is to provide an inputting and outputting method and apparatus capable of memorizing the object pictures with a small number of data.
A further purpose of the present invention is to provide an inputting and outputting method and apparatus feasible for converting the image data of object pictures into multivariable vector data and for regenerating the object pictures at an arbitrary position in an arbitrary scale. A further purpose is to provide an inputting and outputting method and apparatus capable of memorizing the input pictures as compressed data and of treating the compressed data in printing machines or computers. A still further purpose is to provide an inputting and outputting method and apparatus suitable for transmitting image data between remote terminals wirelessly or through telephone cables.